#ifndef __M_BINDING_H__
#define __M_BINDING_H__
#include "../mqcommon/mq_logger.hpp"
#include "../mqcommon/mq_helper.hpp"
#include "../mqcommon/mq_msg.pb.h"
#include <iostream>
#include <unordered_map>
#include <mutex>
#include <memory>


namespace bitmq {
    struct Binding{
        using ptr = std::shared_ptr<Binding>;
        std::string exchange_name;
        std::string msgqueue_name;
        std::string binding_key;

        Binding(){}
        Binding(const std::string &ename, const std::string &qname, const std::string &key):
            exchange_name(ename), msgqueue_name(qname), binding_key(key){}
    };
    //队列与绑定信息是一一对应的（因为是给某个交换机去绑定队列，因此一个交换机可能会有多个队列的绑定信息）
    //因此先定义一个队列名，与绑定信息的映射关系，这个是为了方便通过队列名查找绑定信息
    using MsgQueueBindingMap = std::unordered_map<std::string, Binding::ptr>;
    //然后定义一个交换机名称与队列绑定信息的映射关系，这个map中包含了所有的绑定信息，并且以交换机为单元进行了区分
    using BindingMap = std::unordered_map<std::string, MsgQueueBindingMap>;

    //std::unordered_map<std::string, Binding::ptr>;  队列与绑定  ，
    //std::unordered_map<std::string, Binding::ptr>;  交换机与绑定
    //采用上边两个结构，则删除交换机相关绑定信息的时候，不仅要删除交换机映射，还要删除对应队列中的映射，否则对象得不到释放
    
    class BindingMapper {
        public:
            BindingMapper(const std::string &dbfile):
            _sql_helper(dbfile)
            {
                std::string path = FileHelper::parentDirectory(dbfile);
                FileHelper::createDirectory(path);
                _sql_helper.open();
                createTable();
            }

            void createTable() {
                // create table if not exists binding_table(exchange_name varchar(32), msgqueue_name, binding_key)
                std::stringstream sql;
                sql << "create table if not exists binding_table(";
                sql << "exchange_name varchar(32), ";
                sql << "msgqueue_name varchar(32), ";
                sql << "binding_key varchar(128));";
                assert(_sql_helper.exec(sql.str(), nullptr, nullptr));
            }

            void removeTable() {
                std::string sql = "drop table if exists binding_table;";
                _sql_helper.exec(sql, nullptr, nullptr);
            }

            bool insert(Binding::ptr &binding) {
                // insert into binding_table values('exchange1', 'msgqueue1', 'news.music.#');
                std::stringstream sql;
                sql << "insert into binding_table values(";
                sql << "'" << binding->exchange_name << "', ";
                sql << "'" << binding->msgqueue_name << "', ";
                sql << "'" << binding->binding_key << "');";
                return _sql_helper.exec(sql.str(), nullptr, nullptr);
            }

            void remove(const std::string &ename, const std::string &qname) {
                // delete from binding_table where exchange_name='' and msgqueue_name='';
                std::stringstream sql;
                sql << "delete from binding_table where ";
                sql << "exchange_name='" << ename << "' and ";
                sql << "msgqueue_name='" << qname << "';";
                _sql_helper.exec(sql.str(), nullptr, nullptr);
            }

            void removeExchangeBindings(const std::string &ename) {
                // delete from binding_table where exchange_name='';
                std::stringstream sql;
                sql << "delete from binding_table where ";
                sql << "exchange_name='" << ename << "';";
                _sql_helper.exec(sql.str(), nullptr, nullptr);
            }

            void removeMsgQueueBindings(const std::string &qname) {
                std::stringstream sql;
                sql << "delete from binding_table where ";
                sql << "msgqueue_name='" << qname << "';";
                _sql_helper.exec(sql.str(), nullptr, nullptr);
            }

            BindingMap recovery() {
                BindingMap result;
                // select exchange_name, msgqueue_name, binding_key from binding_table;
                std::string sql = "select exchange_name, msgqueue_name, binding_key from binding_table;";
                _sql_helper.exec(sql, selectCallback, &result);
                return result;
            }

        private:
            static int selectCallback(void* arg,int numcol,char** row,char** fields) {
                BindingMap* result = (BindingMap*)arg;
                Binding::ptr bp = std::make_shared<Binding>(row[0], row[1], row[2]);
                //为了防止 交换机相关的绑定信息已经存在，因此不能直接创建队列映射，进行添加，这样会覆盖历史数据
                //因此得先获取交换机对应的映射对象，往里边添加数据
                //但是，若这时候没有交换机对应的映射信息，因此这里的获取要使用引用（会保证不存在则自动创建）
                MsgQueueBindingMap &qmap = (*result)[bp->exchange_name];
                qmap.insert(std::make_pair(bp->msgqueue_name, bp));
                return 0;
            }
        private:
            SqliteHelper _sql_helper;
    };

    class BindingManager {
        public:
            using ptr = std::shared_ptr<BindingManager>;

            BindingManager(const std::string &dbfile):_mapper(dbfile){
                _bindings = _mapper.recovery();
            }

            bool bind(const std::string &ename, const std::string &qname, const std::string &key, bool durable) {
                //加锁，构造一个队列的绑定信息对象， 添加映射关系
                std::unique_lock<std::mutex> lock(_mutex);

                auto it = _bindings.find(ename);
                if (it != _bindings.end() && it->second.find(qname) != it->second.end()) {
                    return true;
                }
                //绑定信息是否需要持久化，取决于什么？ 交换机数据是持久化的，以及队列数据也是持久化的。
                Binding::ptr bp = std::make_shared<Binding>(ename, qname, key);

                if (durable) {
                    bool ret = _mapper.insert(bp);
                    if (ret == false) return false;
                }
                auto &qbmap = _bindings[ename];
                qbmap.insert(std::make_pair(qname, bp));
                return true;
            }

            void unBind(const std::string &ename, const std::string &qname) {
                std::unique_lock<std::mutex> lock(_mutex);

                auto eit = _bindings.find(ename);
                if (eit == _bindings.end()) { return; }//没有交换机相关的绑定信息
                auto qit = eit->second.find(qname);
                if (qit == eit->second.end()) { return; }//交换机没有队列相关的绑定信息

                _mapper.remove(ename, qname);
                _bindings[ename].erase(qname);
            }

            void removeExchangeBindings(const std::string &ename) {
                std::unique_lock<std::mutex> lock(_mutex);

                _mapper.removeExchangeBindings(ename);
                _bindings.erase(ename);
            }

            void removeMsgQueueBindings(const std::string &qname) {
                std::unique_lock<std::mutex> lock(_mutex);

                _mapper.removeMsgQueueBindings(qname);
                for (auto start = _bindings.begin(); start != _bindings.end(); ++start) {
                    //遍历每个交换机的绑定信息，从中移除指定队列的相关信息
                    start->second.erase(qname);
                }
            }

            MsgQueueBindingMap getExchangeBindings(const std::string &ename) {
                std::unique_lock<std::mutex> lock(_mutex);

                auto eit = _bindings.find(ename);
                if (eit == _bindings.end()) { 
                    return MsgQueueBindingMap(); 
                }
                return eit->second;
            }

            Binding::ptr getBinding(const std::string &ename, const std::string &qname) {
                std::unique_lock<std::mutex> lock(_mutex);

                auto eit = _bindings.find(ename);
                if (eit == _bindings.end()) { 
                    return Binding::ptr(); 
                }
                
                auto qit = eit->second.find(qname);
                if (qit == eit->second.end()) { 
                    return Binding::ptr(); 
                }
                return qit->second;
            }

            bool exists(const std::string &ename, const std::string &qname) {
                std::unique_lock<std::mutex> lock(_mutex);

                auto eit = _bindings.find(ename);
                if (eit == _bindings.end()) { 
                    return false; 
                }
                auto qit = eit->second.find(qname);
                if (qit == eit->second.end()) { 
                    return false; 
                }
                return true;
            }
            size_t size() {
                size_t total_size = 0;
                std::unique_lock<std::mutex> lock(_mutex);

                for (auto start = _bindings.begin(); start != _bindings.end(); ++start) {
                    //遍历每个交换机的绑定信息，从中移除指定队列的相关信息
                    total_size += start->second.size();
                }
                return total_size;
            }
            void clear() {
                std::unique_lock<std::mutex> lock(_mutex);
                _mapper.removeTable();
                _bindings.clear();
            }
        private:
            std::mutex _mutex;
            BindingMapper _mapper;
            BindingMap _bindings;
    };

}
#endif
